1, the composition of the ignition coil

The ignition coil is mainly composed of a core, an initial and a secondary coil, a bakelite cover, a porcelain cup and the like.

The core is made of silicon steel and is wrapped in a cardboard sleeve.

The paper sleeve is wound with a secondary coil, and the wire is an enameled wire with a diameter of 0.06 to 0.10 mm, and is wound around 11,000 to 23,000 Å.

In order to enhance the insulation, several layers of cable paper are also wrapped on the outside of the secondary winding. The outer surface of the primary winding is beneficial for heat dissipation. The diameter of the enameled wire is generally 0.5-0.8 mm, around 220-330 round, and several layers of insulated cable paper are also wrapped outside.

Ignition coil construction diagram

There is also a steel sleeve for magnetic conduction between the primary coil and the outer casing. The bottom of the casing has an insulating porcelain cup, and the upper part has a bakelite cover. The cover has a low-voltage connection column for connecting the breaker, a high-voltage line jack, a "switch" connector and a "power switch" connector. There is a high-profile edge around the interior of the bakelite cover to ensure the insulation of the high-voltage joint.

The shell is filled with insulating oil or asphalt to enhance insulation and prevent moisture intrusion.

The selection of the ignition coil should be consistent with the polarity of the battery's iron connection, which is beneficial to reduce the operating voltage of the spark plug and improve the ignition performance.

Ignition coil physical map 

2.Second, what are the main performance indicators of the ignition coil?

1、The main performance and test methods of the ignition coil are as follows：

（1）Normal temperature ignition performance

The high-voltage electricity generated by the secondary coil of the ignition coil is connected to the standard three-needle discharger via the distributor. The ignition coil should be continuously continuous on the standard three-needle discharger at different speeds of the distributor. The intermittent spark gap should not be less than the specified value.

If the DQG1009 ignition coil is tested in combination with a dedicated distributor, its normal temperature characteristics are specified as：

1 When the distributor speed is 2500r/min, the continuous uninterrupted spark gap should be no less than 9mm.
2 When the distributor speed is 2500r/min, and 1MΩ shunt resistor is connected in parallel between the electrodes of the standard three-needle discharger, the continuous uninterrupted spark gap should be no less than 6mm.
3 When the distributor speed is 1500r/min, the continuous uninterrupted spark gap should be no less than 12mm.

（2）Thermal ignition performance of the ignition coil

It includes the following two contents：

1 When the ambient temperature of the ignition coil is 70 °C and the specified working speed of the distributor is combined for 3 hours, the test shall be able to maintain the specified continuous uninterrupted spark gap on the standard three-needle discharger. For example, the DQ148A type ignition coil works in combination with the ambient temperature of 70 ° C and the special distributor at 2250 r / min for 3 h. During the test, a continuous uninterrupted spark of 9 mm should be maintained on the standard three needle discharger.

2 After the ignition coil is placed in an incubator at 120 °C ± 50 °C for 1 h in different working conditions, the test for 30 s according to the above method shall work reliably, and no insulation shall overflow after the test.

（3）Cold ignition performance of ignition coil

When the ignition coil is placed in the low temperature box at -40 °C in the non-operating state for 3 hours, it is taken out and tested for room temperature ignition performance within 5 minutes. When the distributor is rotating at 2500r/min, the continuous uninterrupted spark should be no less than 9mm.

2、Performance test conditions

When testing the performance parameters of the ignition coil, it must be provided with certain test conditions, including ignition power supply voltage, ignition signal and test load. These test conditions are used to simulate the specific situation of the actual working process of the car, and have practical physical meaning.

3、Ignition power supply voltage

The ignition supply voltage is used to simulate automotive power supplies, including batteries, alternators, and their regulators. The two work in parallel, the generator is the main power source, and the battery is the auxiliary power source. The generator is equipped with a regulator whose main function is to automatically adjust the voltage of the generator to keep it stable when the generator speed increases. The gasoline engine generally adopts a 12 V electric system. When the engine is started, the battery supplies power to the starter and the ignition system; when the engine is idling, the generator supplies power to all the electric devices except the starter, and charges the battery. In the test of the ignition coil performance parameters, the supply voltages are 6 V, 14 V, 20 V, respectively, and their physical meanings are as follows:

（1）6 V is a limit condition and is suitable for cold start conditions of the engine.

When the engine is started, the battery supplies power to the ignition system. In cold weather, due to the increased viscosity of the lubricating oil, the crankshaft resistance increases, and the viscosity of the electrolyte increases when the battery is cold, causing the internal resistance to increase, causing the battery terminal voltage to drop, reducing the output power of the starter, and spark plugging. The fire energy is weakened, and the temperature of the intake pipe and the cylinder is lowered, so that the fuel gasification is poor and the engine starting is difficult.

(2) 14 V is suitable for normal engine operation.
The alternator supplies power to the ignition system while the engine is idling. When the engine speed and load vary within a wide range, the output voltage of the generator can be greatly changed, and thus the working requirements of the electrical equipment cannot be met. For the above reasons, in order to ensure the normal operation of the electrical equipment and prevent the battery from being overcharged, the alternator must be equipped with a voltage regulator to keep its output voltage stable. The voltage regulator fixes the alternator output voltage near a certain value. For a 12 V system, the voltage is 13.5 to 14.8 V.

(3) 20 V is the limit voltage.
The battery is equivalent to a capacitor with a large capacity. When the generator speed and the power load change greatly, the voltage of the vehicle grid can be kept relatively stable. At the same time, the transient overvoltage appearing in the grid can be absorbed for protection. Electrical equipment, especially electronic components, are not damaged. However, when the regulator is out of adjustment or the generator field current is out of control due to a fault (such as contact bonding or power triode breakdown in the electronic regulator), even if a battery is connected, the terminal voltage will rise above 17 V, as in the case of When the battery is disconnected for some reason, the terminal voltage will be even higher or even 80~100 V. This will cause a lot of damage to the entire vehicle's electrical equipment, and the battery will be prematurely scrapped due to overcharging. Therefore, a protection device must be provided to avoid this phenomenon.

4、Ignition signal

The ignition signal is generated by the ignition signal generator while the engine is operating, and its frequency and duty cycle determine the conduction and turn-off time of the Darlington. The conduction time of the Darlington tube determines the current of the primary coil, thereby determining the amount of ignition energy. In order to ensure that the spark plug is ignited at the right moment, the ignition signal is closely related to the position of the piston in the cylinder, the position of the camshaft and the like. 2.3 Test load, test load mainly includes standard load (1 MΩ/50 pF parallel load, 100 kΩ/50 pF parallel load, 50 pF capacitive load, etc.) and Zener diode discharge load.

The high-voltage load resistor is set to simulate the contamination of the spark plug in different degrees of carbon deposit and lead accumulation. When the engine is working, if there is too much lubricating oil, carbon deposits will be formed on the spark plug insulator. The carbon layer is a conductor with a certain resistance. Therefore, a shunt resistor is connected in parallel between the spark plug electrodes to make the secondary circuit form a closed loop. When the Darlington tube is turned off and the secondary voltage is increased, a leakage current is generated in the secondary circuit, and a part of the electromagnetic energy is consumed, so that the maximum value of the secondary voltage is lowered. When the carbon deposit is severe, the secondary voltage is lower than the spark plug flash voltage due to the serious leakage, forcing the engine to stop working.

The total load of the test load is the sum of the capacitance (including distributed capacitance) of the cable and spark plug used to simulate the ignition system when it is operating on the car engine (actual use).

In the case where the load is an analog load, if the ignition energy is constant, the higher the secondary voltage is, the shorter the spark duration is for the ignition coil, so the spark duration measured when the simulated load is used is used as the test parameter. The standard has no practical significance. Since the maximum value of the secondary voltage of each product is different, to establish the test standard of the product on this parameter, so that the measured spark duration is comparable, the secondary voltage must be clamped to a certain value.

Therefore, when measuring the spark coil spark duration, the same standard analog load cannot be used as the secondary voltage routine measurement, but a dedicated clamp load (Zener diode discharge load) should be used.

三、Ignition coil is always burnt out？why?

1、Ignition coil principle

It consists of a main coil, a secondary coil, a magnetic core, a switching transistor and other auxiliary components. The main coil is charged by the battery, the secondary coil discharges the spark plug, and the triode is responsible for switching. The charging time is controlled by the battery voltage and engine speed to ensure that each charging energy is consistent. The ignition coil has two lines and four lines. The three lines are positive, negative, and switch control (ECU command), and one line has one ignition detection. Line, able to detect if the spark plug is ignited (whether there is a discharge current in the secondary coil).

To put it simply, the ignition coil is a transformer, which is to increase the voltage of several tens of volts to tens of thousands of volts, except that the voltage input to the primary coil is provided by an electronic igniter.

2、Causes of ignition coil burnout

The cause of the ignition coil burnout is mainly the breakdown of the insulation layer or the damage of the switch transistor. The spark plug gap leads to large load of the main coil, large heat generation, fast aging of the insulation layer, small gap of the spark plug, large discharge current of the secondary coil, large heat generation, and aging of the insulation layer. Fast, the assembled ignition coil may have poor durability of the insulating material, large internal resistance of the coil, and low life of the tertiary tube.

If it is always burned out, it will burn out soon after the replacement. What is the reason? Here are some of the following:

1. Look at the generator problem first. If the power generation is too high, the ignition coil is too heavy to burn, but if the power generation is too high, then the body appliances, such as the bulb, will often be damaged; It is not necessary to exclude the quality of the parts, so it is best to first measure the amount of electricity generated.

2. The spark plug gap is too large, adjust the gap or replace the spark plug;

3, the quality of gasoline is not good, try to change the high-grade gasoline;

4, the cylinder compression ratio is wrong, adjust the compression ratio;

5, the computer board has a program failure, you can go to the repair shop to check the car with the computer, and clear the error message. If it doesn't work, it may be that your car's clutch has a problem.

6, the power supply voltage is unstable;

7, the resistance of the high voltage line is not normal, replace the high voltage line;

8, the secondary has a short circuit phenomenon;

9. The primary current of the ignition controller is too high, causing the ignition coil to overheat;

10, subject to high temperatures, high-voltage waves have problems working poorly;

11, a small chance is the problem of the coil itself, you can try another brand;

12, the firearm integrated block works poorly;

The ignition coil itself is a transformer, which is like a transformer in a household appliance. When the voltage changes within a specified range, the transformer will not be burnt. Usually, the transformer is generated when the transformer is overloaded, so this is the case. When solving this problem, we should try to find out the cause of excessive load or component aging.